Abstract

The present work evaluates the amenability of Chrysophyllum albidium (CA) and Heliotropium indicum (HI) leaves extracts for bioprocess application. The plant extracts were initially characterized to determined their phytochemical constituents; alkaloids, flavonoids, saponins and tannins were found to be present. Proximate analysis and physico-chemical parameters such as pH, density, viscosity and solubility were evaluated and discussed. Degree of solubility of extracts increase with increased in temperature from 30°C - 60°C which indicates the water absorption characteristic of plant extracts while organic solvent (ethanol and acetone) gives higher values of solubility as compared to distilled water. The rheological and biodegradability of extracts were studied, CA showed a shear-thickening behaviour while HI gives a shear-thinning behaviour, rapid biodegradation occurs in the formulated plant extracts during OECD marine BOD tests. FTIR analyses were used to characterize the bio-active compounds present in the leaves extracts.

Keywords

Introduction

A more bio-based economy offers hope for developed and
developing countries, there is a world-wide growing appreciation that
the management and utilization of natural resources need to improve
[1]. Plants are available in nature and considered as the most natural of
all the other natural things. They are attracted to the scientific
communities due to their environmental benefits in areas such as
household products, environmental clean-up, food processing and
health [2,3].

Due to its natural origins, Plant offers a new paradigm for
bioprocess industry to develop new products, substantially reduced
processing costs, environmental impacts and open new markets for
bio-based materials. They leads the way in cross-disciplinary research
and thereby becoming indispensable because of advancement in green
chemistry [1] and molecular biological studies so as to ensure
maximum benefits with the least risk [4].

Most countries in West Africa especially Nigeria are richly blessed
with forests and luxuriant pastures, among which contain plant origin
with bioactive and antioxidative capacities. Chrysophyllum albidium and Heliotropium indicum are the most popular plants, their natural
occurrence have been reported in diverse zones in Nigeria but has not
been maximally utilized. Chrysophyllum albidium (African star apple)
plant is a forest tree widely known for its fleshy pulp of the fruits while
the popularity of Heliotropium indicum also known as Cock’s comb is
one of the most popular leguminous plants and vegetables used as
spice because of the distinct, pleasant aroma it releases during cooking formulations in Northern Nigeria. Most of the compounds extracted
from these plants are widely used in traditional applications such as
household formulations and herbs.

The aim of this research work is to characterize the extracts of Chrysophyllum albidium and Heliotropium indicum leaves, and to
further determine the physico-chemical and rheological properties of
the bioactive extracted compounds of the leaves.

Materials and Methods

Aerial parts of plant comprising of the leaves, stem and flowers were
collected and identified as Chrysophyllum albidium (Family:
Sapotaceae) and Heliotropium indicum (Family: Boraginaceae)
respectively at the herbarium unit, Department of Biological Sciences,
Ahmadu Bello University, Zaria, Nigeria. The leaves were carefully
removed from its plant; washed, air-dried under shade for seven days,
pestled and pulverized into fine powder before stored in a closed
container at room temperature for further use.

Aqueous extracts of Chrysophyllum albidium (CA) and Heliotropium indicum (HI) leaves were extracted using solvent
extraction method, while BDH analytical grade of ethanol was used as
solvent in the Soxhlet apparatus, consist of a round bottom flask,
thimble, extraction chamber, condenser and siphon arm. Concentrate
using vacuum rotary evaporator. The percentage yield was estimated
with reference to the weight of the ground leaves (eq. 1).

Phytochemical screening of crude extracts was carried out in order
to identify the phytochemicals present using the standard procedure described by [5-8] while the proximate analysis of leaves nutrient
compositions was carried out using the standard methods described by
[9].

Physicochemical parameters of crude extracts were determined in
accordance with the standard methods of Analytical Chemists [10] as
follows 0.5 g of extracts was dissolved in 50ml of distilled water; colour
and odour using sight and smelling techniques, pH using calibrated
digital pH meter (Model pHS-25), and density using pycnometer. Also,
viscosity and solubility was evaluated using the methods of non-
Newtonian fluid [11] while solubility as described by [12]. Also,
Biodegradation tests of crude extracts were carried out using closed
bottle (oxygen demand) tests adopting the Azide modification of the
Winkler method in accordance with OECD 306 Marine BOD [13]
while FTIR analysis was used to identify the functional groups present
in the crude extracts in preparation with KBr salt described by [12].

Results and Discussion

The yield percentage of 13.39% and 7.99% values were obtained for Chrysophyllum albidium (CA) and Heliotropium indicum (HI) leaves
(Table 1), this gave a high yield of extracted products. Although, the
slight difference in the yield of extracted products of each plant might
be due to the degree of solubility in the polar solvent used during
extraction [14].

Sample

Weight of powdered sample (g)

Weight of sample extract (g)

% yield

CA

290

38.85

13.39

HI

290

52.16

17.99

Table 1: % yield of extracts of the plants.

The results of the phytochemical screening of CA and HI plants
extracts are presented using Tables 2 and 3. From the results obtained,
the investigations into the qualitative phytochemical of the plant leaves
extract showed the presence of active phytochemicals constituents
while Chrysophyllum albidium showed the presence of tripenes and Heliotropium indicum for steroids only. Although, the presence of
these secondary metabolites are the basic of physiological activity and
all tested extracts exhibited physiological bioactive properties [15].
This supports its continual uses as household formulations and herbs
[8].

Phytochemicals

Qualitative

Quantitative (%w/w)

Alkaloid

+

0.62

Flavonoid

+

86.44

Saponin

+

16.65

Tannin

+

1.65

Steroid

-

-

Terpenoids

+

-

Table 2: The results of phytochemicals screening of extracts of the CA leaves.

Phytochemicals

Qualitative

Quantitative (%w/w)

Alkaloid

+

1.04

Flavonoid

+

96.25

Saponin

+

24.90

Tannin

+

2.05

Steroid

+

-

Terpenoids

-

-

Key: + = Phytochemical present
- = Phytochemical absent

Table 3: The results of phytochemicals screening of extracts of the HI leaves.

Also, the investigation into the proximate analysis of CA and HI
leaves is shown in Table 4. The results shows that CA and HI contained
varied contains varied percentage amount of nutrient compositions
that are of commercial interest and will support better utilization in
domestic industries. Carbohydrate has the highest value while
moisture has the least value for the plants employed in this study.
Although, the high ash content of Chrysophyllum albidium (CA)
indicates that the leaves is rich in mineral elements while the low
moisture content in Heliotropium indicum (HI) would hinder the
growth of microorganism and promotes storage life.

Components

CA (%)

HI (%)

Moisture

8.45

3.65

Ash

21.91

6.30

Crude lipid

17.28

30.17

Crude Protein

12.23

6.99

Crude fibre

15.4

16.95

Carbohydrate

40.13

52.89

Table 4: The results of the proximate analysis of the leaves of the plants.

The investigations into the physicochemical properties are
summarized using Table 5. Chrysophyllum albidium (CA) has average pH value of 5.67 while 6.31 was recorded for Heliotropium indicum (HI) which indicates a slightly acidic nature of the extracts; the former has a pale-yellow in colour with a pleasant odour and solid appearance
while the latter showed greenish-brown colour with an honey odour
with semi-solid in appearance. CA has higher average density value of
1.14 compared to 1.08 recorded for HI. This slight difference in density might be due to bio-extracts appearance which tends to affects some of
its physical properties such as weight which has a greater tendency on
density.

Parameters

CA

HI

pH (29°C)

5.67

6.31

Colour

Pale-Yellow

Greenish- Brown

Odour

Pleasant

Honey

Appearance

Solid

Semi-solid

Density(29°C kgm-3)

1.14

1.08

Viscosity(29°C PaS)

1504

302

Solubility (%w/v)

a. Distilled water (29°C)

0.51

10.32

b. Distilled water (60°C)

1.96

11.98

c. Ethanol

5.95

9.26

d. Acetone

4.71

9.01

Table 5: Physicochemical properties of the plant crude extract.

The obtained values of the investigation into the kinematic viscosity
of bio-extracts shows that CA is highly viscous with average value of
1504 mPa·s compared to 302 mPa·s recorded for HI crude extracts, this
indicates that it takes longer time for CA extracts to flow under same
gravity through the calibrated spindle (orifice) of the automated digital
viscometer (Model: KVDV-1) at room temperature. Also, from the
recorded values of solubility, it is evident that the solubility of the plant
extracts in distilled water increases with increase in temperature. This
is an indication of the water absorption characteristic of plant extracts
as a result of increased degree of solvent-molecule interaction.
However, CA is very slightly soluble in distilled water (0.51%) but
soluble in ethanol (5.95%) and acetone (4.71%) while HI is freely
soluble in distilled water (10.32%) but soluble in ethanol (9.26%) and
acetone (9.01%) at room temperature. The measured solubility of the
plant extracts in various solvents can be explained as follow. As a rule,
polar compounds are soluble in polar solvents while non-polar
compounds are soluble in non-polar solvents. Although, water is a
universal solvent, its ability to dissolve polar compounds has been
strongly established and is attributed to its high dielectric constant.
Ethanol and acetone are organic solvent. However, ethanol can ionize
to produce hydroxyl ion (OH-). Consequently, the dielectric constant
of ethanol is relatively higher than acetone; therefore ethanol is able to
dissolve the plant extracts to some extent [12].

An important mechanical property of fluids is viscosity, which is the
basic consideration in food industry such as pasteurization,
evaporation, drying and aseptic processing. After, the rheological
study of the bio-extracts from 30°C - 55°C (Figure 1), it was found that
the CA and HI are not ideally viscous; the internal flow resistance of
the extracts is dependent on the external force which is acting upon the
fluid changes with temperature (Figure 1). CA crude extract showed
increasing trend of viscosity from 1833 mPa·s (40°C) up to 4501 mPa·s
(55°C) which indicates a shear- thickening behaviour, while HI
extracts showed decreasing trend of viscosity from 377 mPa·s (40°C ) down to 347 mPa·s (55°C) and indicates shear- thinning behaviour
[16,17]. Chrysophyllum albidium crude extract show its ability to give
structure by the formation of gel during heating and cooling without
breaking the structure.

Figure 1: Rheological behaviour of extracts.

The Biochemical Oxygen Demand (BOD) investigations gave a
general clear trend of decrease in oxygen level reduced with increased
in incubation time indicating that biodegradation occurs in
formulated plant extracts (Figure 2). CA and HI extracts indicates
rapid degradability as oxygen level were found to be 2 ppm and 1 ppm
values after 28 days, therefore are not toxic to plant and animal, micro
and macro organisms. This is consistent with the European Centre for
Ecotoxicology and Toxicology of Chemicals (ECETOC) statement that a chemical that is readily biodegradable in fresh will also be degradable
in marine environments [18].

Figure 2: BOD of formulated plant extracts.

The frequencies of the IR adsorption spectra of plants extract are
presented in Figures 3 and 4. From the results obtained, it was
observed that the FTIR spectrum of Chrysophyllum albidium indicated the presence of functional groups, notably, the C-H bends at
1456.35 cm-1, the C=C stretch at 1616.24 cm-1 and 2360.41 cm-1, and
the OH stretches at 3398.13 cm-1, while the FTIR spectrum of Heliotropium indicum indicated the presence of some functional
groups, notably, the C-I stretch at 490.14 the C-Br stretch at 516.62, the
C-H bends at 824.83 cm-1, 668.25 cm-1, 2923.03 cm-1, the C-Bl stretch
at 824.83 cm-1, the C-O stretches at 1057.84 cm-1, the C=C stretch at
1615.72 cm-1 and 2360.41 cm-1, C=O stretches at 1733.33 cm-1 and the
OH stretches at 3383.83 cm-1, 3734.83 cm-1 and 3820.39 cm-1,
respectively. The peak of these notable functional groups as present
indicates its likelihood as a potential source for environmental friendly
bioprocess with application in corrosion science and pharmaceutical
drug development.

Figure 3: The IR spectrum of CA.

Figure 4: The IR spectrum of HI.

Conclusion

This work encompasses biochemical characterization of extracts
obtained from African Star Apple (Chrysophyllum albidium) and
Cock’s Comb (Heliotropium indicum) plants; from the results and
discussions the following conclusions were made:

Based on the extractable components the leaves can be classified as
high yielding. Their colour and odour are agreeable. None of the
extracts had offensive odour.

The polar extracts of Chrysophyllum albidium and Heliotropium
indicum leaves can serve as viable source for bioprocess applications as
indicated by the presence of secondary metabolites and FTIR peaks.

Chrysophyllum albidium leaves possess immense potential to act in
context of food systems and excipient. Further work on its rheological
properties can be explored.

Oral consumptions of Chrysophyllum albidium and Heliotropium
indicum leaves cannot lead to any health hazards as shown by its rapid
biodegradation.

References

Reports on the application of biotechnology to industrial sustainability– A Primer (2011) Organization for Economic Co-operation and Development (OECD).

Eddy NO, Ameh PO, Danclementino O, Odiongenyi A (2014) Adsorption and chemical studies on the inhibition of the corrosion of aluminium in hydrochloric acid by Commiphoraafricana gum. International Journal of Chemical, Materials and Environmental Research 1: 16-28

Principles and strategies related to the testing of degradation of organic chemicals, Organization for Economic Cooperation and Development Environment Directorate (OECD), Joint Meeting of the Chemicals Committee and the Working Party on Chemicals, Pesticides and Biotechnology. Part 1, ENV/JM 22, 12th August, 2005.

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Review summary

Chloe MathewPosted on Sep 29 2016 at 3:31 pm
The authors carried out various analyses to access the active components of ethanolic leaf extracts of Chrysophyllum Albidium and Heliotropium Indicum. The article provides information regarding the role these leaf extracts in bioprocess applications.